Synthesis of C3-epi-virenose and anomerically activated derivatives.

A 9-step synthetic route to a protected form of the C3-epimer of virenose from D-fucose is described. C3-epi-virenose is the carbohydrate unit of the bioactive polyketide elsamicin B and part of the carbohydrate unit of elsamicin A. The developed route enabled preparation of anomerically activated forms of this unique C6-deoxy sugar, including derivatives with 1-acetyl, 1-acetylthio, 1-trichloroacetimidate, 1-bromo, and 1-fluoro substituents.